The present invention relates to a volute, double suction pump, and more particularly to the design of the wearing ring of the pump.
Volute pumps are frequently used to pump abrasive liquids found in industrial, municipal and marine industry services. Volute pumps are particularly well-suited to service these industries because the volute shape of the pump allows it to operate at capacities above or below design capacity or at interrupted high head.
Volute pumps are designed with two separate sections: the inlet volute and the discharge volute. These two volutes are joined together at the impeller through the use of a wearing ring. Typically, the wearing ring acts to guide the flow of fluid into the impeller eye and decrease the recirculation of fluid through the pump. Wearing rings also act to maintain proper impeller hub clearance, maintain pump performance, protect the pump casing and impeller from excess wear and increase pump efficiency.
Often, the inlet volute of the pump is designed so that a portion of the volute wall follows the contour of the discharge volute. In this type of design, a valley is formed in the inlet volute (See FIGS. 2, 3 and 5). Analysis of the fluid flow through these type of pumps indicates that the valley creates a dead zone in the flow of fluid as it passes over this region. This dead zone creates a separation in the flow of fluid and thus produces non-uniform flow into the eye of the impeller, causes excessive operational noise, and inhibits the pump's efficiency.
In the efficient design of double suction pumps, it is necessary to fill in the suction passage, or alternatively, a portion of the suction passage has to wrap around the discharge volute. In the past, this was not deemed cost effective or necessary, as extra coring in the molding process at the foundry would be necessary.
It has recently been determined, however, that efficient pump design dictates that the valley formed in the suction passage wall be filled, since as fluid flows passes the valley flow separation occurs causing eddies or secondary flow. This results in the development of low pressure areas, creating unwanted noise and loss of efficiency. In pumps designed in accordance with the present invention, suction flow into the eye of the impeller is improved due to the prevention of flow separation.